Copying machines, facsimile machines, document scanners and other such systems are provided with a paper transport system for transporting documents to a scanning section. Typically, these paper transport systems employ a tray to support input documents. The input documents vary in type, size and quality. Certain types of these documents do not slide readily. For example, papers that have been subjected to much handling, special-delivery postal slips and other such documents do not slide across each other readily and are thus difficult to feed.
Conventional feed-in trays are adapted to be tilted or positioned at various angles. When a conventional feed in tray is set in a horizontal position, the documents which do not readily slide cannot be fed smoothly. In order to feed these documents smoothly, it is necessary to tilt the feed-in tray substantially. However, when the feed-in tray is set with a large entry angle, the documents reach the next section of the document path with a correspondingly large entry angle. If the entry angle is too large a high incidence of document jamming occurs.
Thus a user of the prior art document transport system is faced with a dilemma. If the entry angle is set low, there is little jamming, but certain documents will not feed smoothly from the tray. If the entry angle is set high, then documents slide readily from the tray, but there is a high incidence of document jamming. The reason for document jamming in the prior art transport system can be better understood by reference to FIG. 1.
Referring now to FIG. 1, there is shown a cross sectional view of a prior art paper transport apparatus 10. The transport apparatus 10 comprises a feed-in tray 12, a feed roller 14, a retard roller 16, a tray latch 18, and a document guide 20. The feed-in tray 12 can be set to different discrete angles up to a position shown in dashed lines and designated 12a. This change of angle of the feed-in tray 12 increases the angle of entry of the tray 12 relative to the document guide 20. It can be seen that documents (not shown) will slide readily on the feed-in tray 12a, but there is a substantial change in direction of the documents along the document guide 20 in the region near the feed roller 14. This change in direction contributes to document jamming.
It is desirable therefore to provide a document transport apparatus which permits a user to feed documents which do not readily slide into a machine without encountering document jamming.